Brute force method of arriving at values for modular hashing of a small set of strings

Exercise4Mod.java

//Borrowed from https://github.com/reneargento/algorithms-sedgewick-wayne/blob/master/src/chapter3/section4/Exercise4.java
import java.util.ArrayList;                                                                                                        
import java.util.HashSet;                                                                                                          
import java.util.Set;                                                                                                              
                                                                                                                                   
/**                                                                                                                                
 * Created by Rene Argento on 19/07/17.
 * Modified on 10/30/2019
 */                                                                                                                                
public class Exercise4Mod                                                                                                          
{                                                                                                                                  
                                                                                                                                   
    public static void main(String[] args)                                                                                         
    {                                                                                                                              
        Exercise4Mod exercise4 = new Exercise4Mod();                                                                               
        int[] values = exercise4.perfectHashFunction();                                                                            
                                                                                                                                   
        if (values != null)                                                                                                        
        {                                                                                                                          
            System.out.println("a = " + values[0]);                                                                                
            System.out.println("m = " + values[1]);                                                                                
        }                                                                                                                          
    }                                                                                                                              
                                                                                                                                   
    private int[] perfectHashFunction()                                                                                            
    {                                                                                                                              
        int[] values = new int[2];                                                                                                 
                                                                                                                                   
        String[] names10 = {"BritCo", "Albert", "Saskat", "Manito", "Ontari", "Quebec", "NewLab", "NewBru", "NovSco", "PrinEd"};   
        String[] names7 = {"BritCo", "Albert", "Saskat", "Manito", "Ontari", "Quebec", "NewLab"};                                  
        String[] namesRand = {"YaLiWA", "OStREn", "qsiaTL", "PqbCvs", "ZAIore", "AgEEwq", "hjIcxM", "rtivol", "xwuqoH", "ZoKvwe"}; 
                                                                                                                                   
        for(int m = 2; m <= 100; m++) {                                                                                            
            for(int a = 1; a <= 1000; a++) {                                                                                       
                Set<Integer> hashes = new HashSet<>();                                                                             
                                                                                                                                   
                //for(int i = 0; i < names.length; i++)                                                                            
                //for(int i = 0; i < names.length; i++)                                                                            
                for(int i = 0; i < names7.length; i++)                                                                             
                {                                                                                                                  
                    ArrayList sum_hash = hashCodeFunction(a, names7[i], m);                                                        
                    if(hashes.add((Integer)sum_hash.get(1)))                                                                       
                    {                                                                                                              
                        System.out.println("Name: " + sum_hash.get(2));                                                            
                        System.out.println("Sum: " +  sum_hash.get(0));                                                            
                        System.out.println("Hash: " +  sum_hash.get(1));                                                           
                    }                                                                                                              
                }                                                                                                                  
                                                                                                                                   
                if (hashes.size() == 10) {                                                                                         
                    //Perfect hash function found                                                                                  
                    values[0] = a;                                                                                                 
                    values[1] = m;                                                                                                 
                    return values;                                                                                                 
                }                                                                                                                  
            }                                                                                                                      
        }                                                                                                                          
                                                                                                                                   
        return values;                                                                                                             
    }                                                                                                                              
                                                                                                                                   
    private ArrayList hashCodeFunction(int a, String k, int m)                                                                     
    {                                                                                                                              
      ArrayList retval = new ArrayList(3);                                                                                         
      retval.ensureCapacity(3);                                                                                                    
      System.out.println("retval size: " + retval.size());                                                                         
      int sum = 0;                                                                                                                 
      for (int i = 0; i < k.length(); i++)                                                                                         
      {                                                                                                                            
        char c = k.charAt(i);                                                                                                      
        sum += c;                                                                                                                  
      }                                                                                                                            
      int hash = (a * sum) % m;                                                                                                    
      retval.add(0, sum);                                                                                                          
      retval.add(1, hash);                                                                                                         
      retval.add(2, k);                                                                                                            
      return retval;                                                                                                               
    }                                                                                                                              
}